1. Field of the Invention
The present invention relates to a battery pack formed by arranging and containing a plurality of cell modules in parallel to each other in a cell box.
Priority is claimed on Japanese Patent Application No. 2005-176227, filed Jun. 16, 2005, the content of which is incorporated herein by reference.
2. Description of the Related Art
A battery pack may be formed by stacking cylindrical cell modules in a cell box in a zigzag form, where each cell module is formed by serially connecting a plurality of unit cells (see Reference Document 1: Japanese Unexamined Patent Application, First Publication No. 2003-308816). In the battery pack disclosed in Reference Document 1, holding members, each having a polygonal section, are attached to the outer periphery of each cell module at specific intervals along the axis of the cell module, and a plurality of the cell modules are stacked in a zigzag in a manner such that corresponding outer faces of the holding members of adjacent cell modules contact each other.
When the cell modules are stacked in a manner such that corresponding outer faces of the holding members of adjacent cell modules contact each other, heights of upper ends of the cell modules in the top row may not be uniform due to an error in dimension between the holding members, or the like. If the cell modules, arranged in a zigzag while having such an error, are contained in a cell box, the cell modules are unstable in the cell box.
In particular, when such a cell box is installed in a vehicle, the cell modules may be shaken due to the movement of the vehicle, which may cause unnecessary noise.